• 대한치과보철학회지
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• 제28권2호
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• pp.29-51
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• 1990

This study was designed to compre the tensile bond strength of 4-META containging denture base resin to Co-Cr alloys after various surface treatments. Especially the surface treatment of sandblasting the mental with aluminum oxide and treating in oxidizing solution composed of 3% aqueous sulfuric acid with 1% potassium manganate were compared. Effect of surface roughness on bonding was measured after sandblasting with 50um, 300um aluminun oxide and polishing with emery pater. Also the effects of wax and wax solvent on bonding were observed. According to the type of polymerization process, heat-cured Meta-Dent resin and autopolymerizing Meta-Fast resin were used. For some specimnens, the tensile bond strength were measured agter three pre-conditions : 1day after bonding, immersed in water at $75^{\circ}C{\pm}3^{\circ}C$ for 4weeks, under normal ambient condition for 4weeks. The following results were obtained from this study : 1. The bond strengths of resins containing 4-META were significantly higher than those of conventional denture base resins(p<0.05). 2. Autopolymerizing Meta-Fast resin had higher bond strength than heat-cured Meta-Dent, resin(p<0.05). 3. The bond strengths of Biosil and Nobilium to 4-META containging resins were not significally different(p>0.05). 4. Stable adhesion can be achieved when mechanically roughen the metal surface by snadblasting with $50{\mu}m$ aluminum oxide than treating in an oxidizing soluing with potassium manganate(p<0.05). 5. Once the metal surface is contaminated with wax, the bond srtength decreased greatly in spite of wax wash with boiling water. But the bond strength recovered significantly with the use of wax solvent 6. Meta-Dent resin had higher bond strength when roughen the metal surface with $50{\mu}m$ aluminum oxide than with $300{\mu}m$ aluminum oxide(p<0.05). In case of Meta-Fast, resin, the use of $300{\mu}m$aluminum oxide was a little advantageous of bonding, but was statistically insignificant(p>0.05).

• 생물환경조절학회지
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• 제5권1호
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• pp.89-97
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• 1996

수박과 참외를 1995년 6월 1일에 파종하여 6월 7일에 pot에 가식한 후 6월 24일에 greenhouse에 정식하여 2개월 20일 동안 재배하였으며, 이 재배기간 동안 원적외선 방사 bioceramics를 기비와 엽면 살포하는 방법으로 처리하여 다음과 같은 결과를 얻었다. 1. 참외와 수박 모두 생장 초기에는 엽면적 생장에 bioceramic 효과가 없었으나, 정식 20일이 지난 후부터 그 효과가 나타났으며, 참외의 경우에는 처리구 No. 2에서, 수박의 경우에는 처리구 No. 3에서 그 효과가 가장 크게 나타났다. 2. 수박 열매의 bioceramic 효과는 착과 후 초기부터 나타났으며, 중기에 약간 저조하다가 수확 직전인 후기에 그 효과가 두드러지게 나타났고, 처리구 No. 3에서 열매 생장률이 가장 크게 나타났다. 참외의 경우에는 착과 후 초기에 열매 성장률이 가장 컸으며, 중기, 후기로 갈수록 열매 성장률이 점차 감소하는 경향을 보였고, 처리구 No. 3에서 bioceramic 효과가 가장 크게 나타났다. 3. 참외 밀도에 대한 bioceramic 효과는 처리구 No. 3에서 가장 크게 나타났으나, 물보다 적은 0.975g/$\textrm{cm}^2$였고, 수박 밀도에 대한 bioceramic 효과는 처리구 No. 3과 No. 4에서 크게 나타났으며, 물보다 큰 1.031 1.035g/$\textrm{cm}^2$였다. 4. 참외와 수박의 경우 모두 처리구 No. 3에서 당도가 가장 높게 나타났으며, 참외는 Brix 당도계로 12.3이었고, 수박은 11.5였다. 5. 수확 10일 후 참외 열매의 신선도는 처리구 No. 2에서 가장 높게 나타났다. 수박의 경우는 수확 후 50일이 경과하여도 처리구 No. 4의 경우에는 신선도가 100% 유지된 것으로 보아 수박 재배 기간 중 bioceramic 처리가 적절하면 50일 정도의 저장이 가능할 것으로 판단되었다.

• 생태와환경
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• 제34권4호통권96호
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• pp.261-266
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• 2001

이산화탄소 농도가 증가할 때에 북구 이탄 습지에서 나타나는 생지화학적 변화과정을 살펴보았다. 표면 식생을 포함한 온전한 코어를 북웨일스의 이탄습지로부터 채취하여, 높은 이산화탄소농도(700ppm)와 자연상태 (350ppm)환경에서 4개월간 배양하였다. 배양 후, 화학적인 저해제를 이용하여 습지 토양에서 미량기체의 생성과 소비를 측정하였다. 메탄의 경우, 불화메탄($CH_3F$)를 이용하여 메탄 산화율을 결정하였고, 질산화와 탈질작용을 측정하기위해 아세틸렌($C_2H_2$)저해 방법을 적용하였다. 이를 위해, 먼저 각 측정 방법을 습지 시료에 적합하도록 최적화 시켰고, 둘째로 두 수준의 이산화탄소에서 배양한 시료에 이 방법들을 적용하였다. 높은 이산화탄소 농도는 메탄의 생성량을 증가 시켰으나(210대 $100\;ng\;CH_4 g^{-1}\;hr^{-1}$), 메탄 산화의 양도 증가시켜서 (128대 $15\;ng\;CH_4 g^{-1}\;hr^{-1}$) 결국에는 순메탄 방출량에는 변화가 없었다. 아산화질소의 경우에는 증가된 발생량이 탈질 보다는 질산화 과정에서 생성된 것으로 사료된다. 이러한 변화들은 높은 이산화탄소 하에서 조류의 성장이 증가되어 야기된 것으로 추측된다.

• 생태와환경
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• 제53권3호
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• pp.295-303
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• 2020

We investigated the growth response and population regeneration of four halophyte species: Suaeda japonica, Salicornia europaea, Suaeda maritima and Suaeda glauca, when climate change proceeds caused by increased CO₂ concentration and temperature. The plants collected from habitat in 2018 were transplanted into Wagner pots, and cultivated for two years in greenhouse divided into a control (ambient condition) and a treatment (elevated CO₂+elevated temperature). The shoot length of halophytes was measured in July of each year, and the population regeneration rate was measured in October 2019. The shoot lengths of S. japonica and S. glauca had no difference between control and treatment for two years. Those of S. europaea were longer in control than treatment for two years. Those of S. maritima had no difference between control and treatment in 2018 but were longer in control than treatment in 2019. In control, the shoot lengths of S. japonica, S. europaea and S. glauca had no difference between years while those of S. maritima were longer in 2018 than in 2019. In treatment, those of S. japonica, S. europaea and S. maritima were shorter in 2019 than 2018 but S. glauca had no difference between years. The regeneration rates of S. japonica, S. europaea and S. glauca were lower treatment than control, and there was no difference in the regeneration rate of S. maritima. In conclusion, if climate change progresses caused by the increase of CO₂ concentration and temperature, the shoot lengths of S. japonica, S. europaea and S. maritima will be shortened, and the regeneration rate of population will be increased only in the S. maritima.

• 한국재료학회지
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• 제5권7호
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• pp.835-841
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• 1995

Si$_3$N$_4$가 추진기관 연소조건 하에서 흑연의 산화와 마모를 효과적으로 방지하는 다층 코팅재료로 쓰일 수 있도록 하기 위하여 저압화학기상증착법(LPCVD)으로 Si$_3$N$_4$를 코팅할 때의 증착특성에 대해 연구하였다. 흑연 위에 pack cementation방법으로 SiC를 코팅하고 그 위에 저압화학기상증착법으로 Si$_3$N$_4$를 코팅 하였으며, 증착온도와 반응기체입력비를 변화시키면서 이에 따른 증착속도와 표면형상의 변화를 관찰하였다. 증착속도는 증착온도가 높아짐에 따라 처음에는 증가하다가 최대값을 나타낸 후 감소하는 경향을 나타냈으며, 그레인의 크기는 증착온도가 높아짐에 따라 작아지는 경향을 보였다. 한편, 반응기체의 입력비가 20$\leq$NH$_3$/SiH$_4$$\leq$40인 조건에서는 증착속도의 변화나 표면형상의 변화를 관찰할 수 없었다. 증착온도 800~130$0^{\circ}C$ 범위에서 증착된 Si$_3$N$_4$가 비정질상인 것을 XRD로 확인할 수 있었으며 130$0^{\circ}C$, 질소 분위기에서 2시간 동안 열처리하여 결정상인 Si$_3$N$_4$를 인을 수 있었다.

• 한국대기환경학회지
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• 제23권6호
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• pp.675-688
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• 2007

To characterize organic and elemental carbon (OC and EC), and water-soluble organic carbon (WSOC) contents, daily $PM_{2.5}$ measurements were performed in August 2006 (summer) and Jan $11{\sim}Feb$ 12 2007 (winter) at an urban site of Gwangju. Daily size-segregated aerosol samples were also collected for WSOC analysis. No clear seasonal variations in EC and WSOC concentrations were observed, while seasonal differences in OC concentration, and OC/EC and WSOC/EC ratios were shown. The WSOC/OC ratio showed higher value in summer (0.56) than in winter (0.40), reflecting the greater enhancement of secondary WSOC formation at the site in summer. Secondary WSOC concentrations estimated using EC tracer method were in the range $0.0{\sim}2.1\;{\mu}g/m^3$ (average $0.42\;{\mu}g/m^3$) and $0.0{\sim}1.1\;{\mu}g/m^3\;(0.24\;{\mu}g/m^3)$, respectively, accounting for $0{\sim}51.6%$ (average 16.8%) and $0{\sim}52.5%$ (average 13.1 %) of the measured WSOC concentrations in summer and winter. Sometimes higher WSOC/OC ratio in winter than that in summer could be attributed to two reasons. One is that the stable atmospheric condition often appears in winter, and the prolonged residence time would strengthen atmospheric oxidation of volatile organic compounds. The other is that decrease of ambient temperature in winter would enhance the condensation of volatile secondary WSOC on pre-existing aerosols. In summertime, atmospheric aerosols and WSOC concentrations showed bimodal size distributions, peaking at the size ranges $0.32{\sim}0.56\;{\mu}m$ (condensation mode) and $3.2{\sim}5.6\;{\mu}m$ (coarse mode), respectively. During the wintertime, atmospheric aerosols showed a bimodal character, while WSOC concentrations showed a unimodal pattern. Size distributions of atmospheric aerosols and WSOC with a peak in the size range $0.32{\sim}0.56\;{\mu}m$ were observed for most of the measurement periods. On January 17, however, atmospheric aerosols and WOSC exhibited size distributions with modal peaks in the size range $1.0{\sim}1.8\;{\mu}m$, suggesting that the aerosol particles collected on that day could be expected to be more aged, i.e, longer residence time, than the aerosols at other sampling periods.

• 농약과학회지
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• 제9권3호
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• pp.221-230
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• 2005

국내에 서식하는 주요 물벼룩에 대한 독성시험기준 마련의 필요성에 따라 국내환경에서의 대표성, 실내사육가능성 및 독성시험에 적합한 크기 등을 고려하여 선발된 4종의 한국산물벼룩(Daphnia sp., Daphnia obtusa, Moina macrocopa, Simocephalus vetulus)과 Daphnia magna를 대상으로 사육온도(16, 20, 24, $28^{\circ}C$)에 따른 번식영향을 조사하였다. 그 결과 실험에 사용한 5종 물벼룩 모두 온도가 높을수록 탈피횟수, 새끼출산수 및 내적자연증가율이 증가하고 성체가 되는데 걸리는 기간과 생존율은 낮아지는 경향을 보였다. 따라서 높은 온도조건에서 높은 내적자연증가율을 보여줌에도 불구하고 고온에서의 높은 모체사망율을 고려한다면 대부분은 $20^{\circ}C$ 내외가 가장 적절한 사육온도임을 알 수 있었다. 다만 D. obtusa의 경우에는 $16^{\circ}C$에서 더 높은 모체생존율을 보여주었으며 내적자연증가율도 $20^{\circ}C$와 비교하여 큰 차이가 없어 $16^{\circ}C$ 내외가 더 적절한 온도인 것으로 판단되었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.250-250
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• 2012

Recently, multiferroic materials have attracted much attention due to their fascinating fundamental physical properties and potential technological applications in magnetic/ferroelectric data storage systems, quantum electromagnets, spintronics, and sensor devices. Among single-phase multiferroic materials, $BiFeO_3$, in particular, has received considerable attention because of its very interesting magnetoelectric properties for application to spintronics. Enhanced ferromagnetism was found by Fe-site ion substitution with magnetic ions. In this study, $BiFe_{1-x}Ni_xO_3$ (x=0 and 0.05) bulk ceramic compounds were prepared by solid-state reaction and rapid sintering. High-purity $Bi_2O_3$, $Fe_3O_4$ and NiO powders were mixed with the stoichiometric proportions, and calcined at $450^{\circ}C$ for 24 h to produce $BiFe_{1-x}Ni_xO_3$. Then, the samples were directly put into the oven, which was heated up to $800^{\circ}C$ and sintered in air for 20 min. The crystalline structure of samples was investigated at room temperature by using a Rigaku Miniflex powder diffractometer. The Raman measurements were carried out with a Raman spectrometer with 514.5-nm-excitation Ar+-laser source under air ambient condition on a focused area of $1-{\mu}m$ diameter. The field-dependent magnetization and the temperature-dependent magnetization measurements were performed with a vibrating-sample magnetometer. The x-ray diffraction study demonstrates the compressive stress due to Ni substitution at the Fe site. $BiFe_{0.95}Ni_{0.05}O_3$ exhibits the rhombohedral perovskite structure R3c, similar to $BiFeO_3$. The lattice constant of $BiFe_{0.95}Ni_{0.05}O_3$ is smaller than of $BiFeO_3$ because of the smaller ionic radius of Ni3+ than that of Fe3+. The field-dependent magnetization of $BiFe_{0.95}Ni_{0.05}O_3$ exhibits a clear hysteresis loop at 300 K. The magnetic properties of $BiFe_{0.95}Ni_{0.05}O_3$ were improved at room temperature because of the existence of structurally compressive stress.

• 수산해양기술연구
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• 제39권4호
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• pp.269-275
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• 2003

제주도 연안 정치망의 여름철 주 어획대상인 잿방어를 실험어로 하여, 음향을 이용한 어군행동 제어, 음향순치 등 바다목장 조성을 위한 어군의 관리, 사육, 어획기술에 이용할 기초자료를 제공할 목적으로 육상수조에서 수중 가청 저주파음과 전기충격을 이용하여 음향 학습 시킨 후, 주파수와 음압을 변화시켜가면서 잿방어의 섬전도를 도출 하여 심박간격의 변화로부터 청각문턱치, 청각임계비를 측정하였다. 자연환경소음에서 잿방어의 청각문턱치는 측정 주파수 80∼800 HZ의 수중 가청음을 모두 인식하였고, 측정 주파수 200∼500 HZ 에서 청각 감도가 양호하였으며, 측정 주파수 300 Hz에서 평균 음압 94.5 dB, 표준편차 4.5 dB로 가장 낮은 청각문턱치를 보였다. 평균 음압을 65 dB, 70 dB, 75 dB의 3단계로 변화시킨 백색잡음 방성으로 측정한 잿방어의 청각임계비는 측정 주파수 80, 100, 200, 300, 400, 500, 800 HZ에서 각각 평균 음압 45.9, 52.8, 42.5, 36.4, 38.6, 39.4, 44.4 dB이었다. 측정 주파수 300 HZ, 400 HZ 그리고 500 HZ 에서는 백색잡음 중에서 측정음을 식별하는 능력이 다른 측정 주파수에 비하여 우수했다. 잿방어가 주파수 300 HZ의 수중 가청음을 충분히 인식하기 위해서는 최저 100 dB 이상의 음압 강도가 펼요하며 환경 소음이 존재하는 환경에서는 소음 스펙트럼 음압 레벨보다 약 35 dB 이상 크게 방성할 펼요가 있다.

• Fisheries and Aquatic Sciences
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• 제13권1호
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• pp.63-70
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• 2010

Two feeding experiments were conducted to investigate the effects of dietary genetically modified (GM) soya and com on growth performance, feed utilization and body composition of juvenile olive flounder, Paralichthys olivaceus and rockfish, Sebastes schlegelii. For each fish species, four isonitrogenous (50% crude protein) and isocaloric (4.1 kcal/g) diets (designated as nGM soya, GM soya, nGM com and GM com) were formulated to contain 20% non-GM (nGM) and GM soya and com. Thirty olive flounder (initial body weight, 15.4${\pm}$0.4 g) and fifty rockfish (initial body weight, 3.1${\pm}$0.02 g) were distributed in each 400 L tank (200 L water) in a flow through system. Each experimental diet was fed to triplicate groups of fish to visual satiation, twice a day (9:00 hand 17:00 h) for 6 weeks. Growth performance was measured every three weeks. No effects of GM feedstuffs on survival were observed. Dietary inclusion of GM feedstuffs did not affect growth performance and feed utilization of fishes, except for rockfish fed GM com. Rockfish fed the GM com diet showed higher weight gain, daily feed intake and daily protein intake than did fish fed the nGM com diet, but no significant differences were observed in final body weight between the dietary treatments. Condition factor, hepatosomatic index, visceral somatic index and body composition were not altered by the inclusion of GM feedstuffs. These results indicate that dietary inclusion of GM soya and com could have no effects on growth performance and feed utilization of juvenile flounder and rockfish. Lower weight gain and feed intake in flounder and rockfish fed the diets containing 20% soya were likely due to anti-nutritional factors, rather than transgenic factors in the feedstuffs. Dietary inclusion of GM soya and com at the level tested did not alter the body composition of fishes. Further studies to investigate the effects of GM feedstuffs on health conditions and the development of fishes, as well as those of residue of transgenic fragments in ambient environments and in animals are necessary for safe use of the ingredients in aquaculture.